bête noire

The  BANE  OF  ONE’S  EXISTENCE;  a  persistent  nuisance. French for “black beast,” this cliché is older than the synonymous PAIN  IN THE  NECK and THORN  IN  ONE’S  SIDE. It dates from the first half of the nineteenth cen- tury and became popular (in English) during the long period when French was  the  principal  language  of  culture  and  diplomacy.  It  is  on  its  way  to obsolescence.